A heat shield film including a substrate and a hard coat layer formed on at least one surface of the substrate by curing an active energy ray-curable resin composition having the ability to absorb infrared rays (heat rays) (heat shield performance) is proposed as a protective film or a heat shield film for components of displays such as image displays (e.g., liquid crystal displays, CRT displays, plasma displays, electroluminescence (EL) displays), and touch panels, and for window panes of buildings, cars, and trains.
Recently, it has also been proposed to use, as infrared absorbers, composite tungsten oxide fine particles with high heat shield performance (e.g., refer to Patent Literatures 1 and 2).
Patent Literature 1 discloses a technology in which adhesion, reworkability, and suppression of chromaticity change caused by spectral characteristics change in a high-temperature, high-humidity environment at 60° C. and 90% RH can be achieved using composite tungsten oxide fine particles and an acrylic pressure-sensitive adhesive resin containing carboxy groups as main crosslinking groups and having an acid value of 0.6 to 30 mgKOH/g. In this technology, however, the compatibility between the resin and the fine particles is insufficient, the initial haze is high, and an increase in haze in a high-temperature environment or a high-temperature, high-humidity environment cannot be suppressed sufficiently.
Patent Literature 2 discloses a technology in which a dispersion containing cesium-containing composite tungsten oxide (CWO) fine particles and an acrylic pressure-sensitive adhesive resin having an acrylate skeleton and hydroxy groups as main crosslinking groups can provide reduced haze when containing a typical metal compound selected from zinc carbonate, zinc oxide, and magnesium oxide. However, this literature is silent on durability such as resistance to haze increase in a high-temperature, high-humidity environment.